Hypocomplementemia of unknown etiology: an opportunity to find cases of IgG4-positive multi-organ lymphoproliferative syndrome

Clinical Outcomes of IgG4-Related Ophthalmic Disease and Idiopathic Sclerosing Orbital Inflammation

PURPOSE

To compare the clinical features, treatment outcomes, and prognoses of immunoglobulin G4-related ophthalmic disease (IgG4-ROD) and idiopathic sclerosing orbital inflammation (ISOI).

METHODS

This retrospective case series included 40 and 22 biopsy-proven cases of IgG4-ROD and ISOI, respectively. The authors reviewed medical charts and images to determine the clinical presentation, involvement pattern, and treatment outcomes. The main outcome measures were differences in disease manifestation, treatment modalities and efficacy, medication-free remission rate, and predictive factors for remission.

RESULTS

The median ages were 51 (range 31-72) and 39 (range 9-73) years in the IgG4-ROD and ISOI groups, respectively. The most frequently involved sites were the lacrimal gland (39 cases, 98%) in IgG4-ROD patients and the extraconal region (15 cases, 68%) in ISOI patients. No significant difference was observed in the initial treatment response between the groups. Medication-free remission was achieved in 22 (55%) IgG4-ROD patients and 10 (45%) ISOI patients; none of the IgG4-ROD patients showed permanent ocular dysfunction, while half of the ISOI patients had permanent visual loss or limited ocular motilities. Multivariate analysis indicated that extraocular muscle enlargement (odds ratio, 0.11; 95% confidence interval, 0.01-0.98) and IgG4:IgG ratio on histopathology (odds ratio, 0.08; 95% confidence interval, 0.01-0.86) were negatively associated with medication-free remission in IgG4-ROD patients.

CONCLUSIONS

Although IgG4-ROD and ISOI share common histological findings of mass-forming sclerosis, IgG4-ROD frequently has a more indolent clinical course, whereas ISOI often demonstrates a more aggressive clinical course, resulting in ocular dysfunction even after remission. Different pathogeneses may account for the different disease characteristics.

Immune Dysregulation in IgG4-Related Disease

Immunoglobin G₄-related disease (IgG₄-RD) is one of the newly discovered autoimmune diseases characterized by elevated serum IgG₄ concentrations and multi-organ fibrosis. Despite considerable research and recent advances in the identification of underlying immunological processes, the etiology of this disease is still not clear. Adaptive immune cells, including different types of T and B cells, and cytokines secreted by these cells play a vital role in the pathogenesis of IgG₄-RD. Antigen-presenting cells are stimulated by pathogens and, thus, contribute to the activation of naïve T cells and differentiation of different T cell subtypes, including helper T cells (Th1 and Th2), regulatory T cells, and T follicular helper cells. B cells are activated and transformed to plasma cells by T cell-secreted cytokines. Moreover, macrophages, and some important factors (TGF-β, etc.) promote target organ fibrosis. Understanding the role of these cells and cytokines implicated in the pathogenesis of IgG₄-RD will aid in developing strategies for future disease treatment and drug development. Here, we review the most recent insights on IgG₄-RD, focusing on immune dysregulation involved in the pathogenesis of this autoimmune condition.

Prognostic factors in IgG4-related disease: a long-term monocentric Chinese cohort study

OBJECTIVES

Patients with IgG4-related disease (IgG4-RD) suffer high relapse rates during long-term treatment, but factors that predict relapse outcomes are not well established. In the present study, we aimed to identify predictive factors for treatment resistance and disease relapse in a Chinese IgG4-RD cohort.

METHODS

This study enrolled 102 patients newly diagnosed with IgG4-RD. Disease prognosis was determined by evaluating disease activity and dosage of glucocorticoids. Predictive factors for refractory and relapsed disease were identified by univariate analysis and Cox regression.

RESULTS

Among the 102 patients, 78 cases received medical treatment with regular follow-up (21 [6-111] months). During the follow-up period, 55 (70.5%) patients sustained clinical remission, and 23 (29.5%) patients suffered refractory or relapsed disease. The relapse rate of the patients with IgG4-RD was significantly higher among patients who stopped taking medicine than among those who continued treatment with glucocorticoids (GC) + immunosuppressor (IM). Serum TNF-α ≥ 13 pg/mL, sIL-2R ≥ 1010 U/mL, total cholesterol < 3.55 mmol/L, low-density lipoprotein < 2.0 mmol/L, IgG ≥ 20.2 g/L, and drug withdrawal were predictive factors for refractory and relapsed IgG4-RD. Multivariate Cox regression revealed that both sIL-2R and TNF-α were independent risk factors for refractory and relapsed disease. The combination of GC and IM treatment was an independent protective factor against refractory and relapsed IgG4-RD.

CONCLUSIONS

High serum levels of sIL-2R and TNF-α may be informative risk factors for refractory and relapsed IgG4-RD. Our data suggest that a combination treatment of GC along with IM may be protective against refractory and relapsed IgG4-RD. Key Points • High sIL-2R and TNF-α levels are informative risk factors for refractory and relapsed IgG4-related disease. • Combination treatment of GC with IM protects against refractory and relapsed IgG4-related disease.

IgG4-Related Disease with Emphasis on Its Gastrointestinal Manifestation

IgG4-related disease is an immune-mediated fibroinflammatory condition with a diverse spectrum of organ involvement, commonly in the pancreas and bile ducts among other organs such as salivary and lacrimal glands. Classic histopathologic findings are the gold standard for confirmation of diagnosis, although diagnosis remains challenging, as biomarkers to date are neither sufficient nor necessary. Glucocorticoids are the most effective initial treatment, generally having a dramatic response, although limited clinical evidence exists regarding effective maintenance therapy. This review summarizes key GI manifestations of this condition for the practicing gastroenterologist and addresses the pathology, disease mechanism, and current therapeutic recommendations.

IgG4-related Disease - A Systemic Disease that Deserves Attention Regardless of One's Subspecialty

IgG4-related disease (IgG4-RD) is an inflammatory condition characterized by a high serum IgG4 concentration and the abundant infiltration of lymphocytes and IgG4-positive plasma cells in the tissue, as well as spatial (diverse clinical manifestations) and temporal (the possibility of recurrence) multiplicities. Since the initial documentation of IgG4-related disease in patients with autoimmune pancreatitis in 2001, a growing body of evidence has been accumulating to suggest that various-virtually all-organs can be affected by IgG4-RD. In general, steroid therapy is effective and is considered to be the first-line treatment for IgG4-RD. The precise mechanism underlying this systemic disorder has remained unknown. Considering that IgG4-RD was specified as being an intractable disease in 2015, further studies are needed to clarify whether IgG4-RD is indeed a distinct disease entity or a complex of disorders of different etiologies and clinical conditions.

New clues to the nature of immunoglobulin G4-related disease: a retrospective Japanese multicenter study of baseline clinical features of 334 cases

Background

The aim was to further characterize immunoglobulin G4-related disease (IgG4-RD) by a large-scale multicenter study of its clinical and laboratory features conducted by multidisciplinary physicians of IgG4-RD in Japan.

Methods

Various specialists retrospectively evaluated IgG4-RD patients diagnosed between 1996 and 2015 in five hospitals by analyzing their baseline clinical features, laboratory, imaging, and pathological test findings, and treatment.

Results

Of the 334 patients listed, 205 were male and median age at diagnosis was 65 years. The mean number of organs involved was 3.2 at diagnosis. The most frequently affected organs were the salivary glands, followed by the lacrimal glands, lymph nodes, pancreas, retroperitoneum/periaorta, kidneys, and lungs. The mean serum level of IgG4 was 755 mg/dl, and more than 95% of patients had elevated serum IgG4 levels. The median serum level of C-reactive protein (CRP) was 0.1 mg/dl and the level was less than 1 mg/dl in 90% of patients. A total of 34.7% of patients had low serum levels of C3. Serum levels of C3 and non-IgG4 IgG, calculated as the total IgG minus IgG4, showed an inverse correlation in patients with kidney lesions, while serum IgG4 levels were not correlated with serum C3 levels. Corticosteroid was administered in 78.0% of patients, and was effective in all.

Conclusions

The serum CRP level is generally low and the serum IgG4 level is elevated in most Japanese IgG4-RD patients, in contrast to western patients. These original findings suggest that these two parameters in IgG4-RD differ in some interesting ways from those hitherto reported in western populations. Additional studies, especially international comparative ones, are needed to elucidate the extent and significance of these differences between populations. Attention will also have to be paid to whether the existence of such differences requires consideration when devising international classification criteria.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1467-x) contains supplementary material, which is available to authorized users.

IgG4-related disease of the rectum

IgG4-related disease is a relatively new disease entity characterized by elevated serum IgG4 levels and marked infiltration of IgG4-positive plasma cells in lesions. Organ enlargement or nodular lesions consisting of abundant infiltration of lymphocytes and IgG4-positive plasma cells and fibrosis are seen in various organs throughout. We encountered a patient with an inflammatory pseudotumor of the rectum, which was histopathologically confirmed to be an IgG4-related disease. The patient was a 28-year-old woman who had constipation for 3 months. The endoluminal ultrasonography showed a lesion that was heterogeneous and low echogenic in lower rectum. The result of colonoscopic biopsy findings was of chronic proctitis with lymphoid aggregates. For a confirmative diagnosis, excision was performed. Histopathological examination represented plasma cell infiltration and fibrosis. Immunohistochemistry revealed prominence of IgG4-positive plasma cells and confirmed the diagnosis of IgG4-related disease. The patient is currently under observation on low-dose oral prednisolone without relapse.

The Immunobiology of Immunoglobulin G4 and Complement Activation Pathways in IgG4-Related Disease

High serum immunoglobulin (Ig) G4 concentration and abundant IgG4-bearing plasma cell infiltration are characteristic features in autoimmune pancreatitis (AIP). AIP is also complicated with a variety of other organ involvements that commonly share marked IgG4-bearing plasma cell infiltration, suggesting the existence of a systemic disease associated with IgG4 currently recognized as IgG4-related disease (IgG4-RD). However, it is controversial whether IgG4 plays a role in the pathogenesis of AIP or IgG4-RD through such characteristic attributes as Fab-arm exchange and rheumatoid factor (RF)-like activity. Hypocomplementemia has been observed in AIP and several other IgG4-RDs. Muraki et al. reported that complements C3 and C4 were decreased in 36 % of patients with AIP, which implicated the complement activation system in disease pathogenesis. AIP patients with a high level of immune complexes showed serum elevation of IgG4-type immune complexes in an active disease stage, elevated serum IgG1 concentration, and decreased C3 and C4 values. This inferred that while IgG4 may have had little contribution to complement activation, IgG1 played a prominent role via the classical pathway. On the other hand, Sugimoto et al. observed that polyethylene glycol-precipitated immune complexes from patients with IgG4-RD and hypocomplementemia had the ability to activate the complement system through both the classical and the mannose-binding lectin pathways and that IgG4 might participate in the complement activation system. Thus, debate continues on which complement activation systems are working in AIP and IgG4-RD and whether they are associated with the pathogenesis of these conditions.

[IgG4-related disease]

IgG4-related disease is a systemic fibroinflammatory syndrome of unknown etiology characterized by local inflammatory swelling and tumefactive lesions in one or several organs. It unifies several diseases previously thought to be unrelated. Recently, diagnostic criteria for the disease have been formulated and were complemented by an international consensus on histopathological assessment. In general, the disease activity can be rapidly controlled by high doses of prednisolone (0.6 mg/kg body weight); however, relapses, either local or in other regions, are frequent during tapering of the steroid dose. Commonly used steroid-sparing agents are only partially effective. Persistent local inflammatory activity may result in permanent organ damage. In refractory cases rituximab treatment has been used with good success. In the long-term care of affected patients a probable increased risk of malignancies (e.g. solid tumors and lymphoma) requires attention.

[IgG4-related disease and renal and urological involvement]

Hyper-IgG4 syndrome, or IgG4-related disease, is an emerging disorder, involving one or more organ(s), and characterized by "storiform" fibrosis and inflammatory lesions with a predominance of IgG4+ plasma cells and increased IgG4 serum levels. Since the first report of auto-immune pancreatitis, numerous organ lesions have been reported and have been found to occur in a same patient including: sialadenitis, dacryoadenitis, lymphadenopathy, liver and biliary tract involvement, and renal and retroperitoneal lesions. Renal involvement was first described in 2004 and usually presents as functional and/or morphological abnormalities. In most cases, renal pathological analysis reveals tubulointerstitial nephritis that is rarely associated with glomerular lesions. Retroperitoneal fibrosis is also a typical feature that may be associated with periaortitis or inflammatory abdominal aortic aneurysm. First line treatment is based on corticosteroid therapy. Short-term outcome is usually favorable. However, patients should be carefully monitored for relapses and long-term complications. Although the multiple organ lesions share common clinical, biological, radiological and pathological features, no consensus diagnostic criteria have yet been validated for IgG4-related disease. Ruling out differential diagnoses is thus mandatory. Our literature review provides nephrologists, urologists and pathologists with key elements that will help in the early diagnosis and proper management of this new and emerging disorder.

[IgG4-related systemic disease: emergence of a new systemic disease? Literature review]

Hyper-IgG4 syndrome, or IgG4-related systemic disease (IgG4-RSD), has been recently characterized by the association of a focal or diffuse enlargement in one or more organs, elevated levels of serum IgG4 and histopathological findings including "storiform" fibrosis and prominent infiltration of lymphocytes and IgG4-positive plasma cells. Pancreas was the first organ involved with sclerosing pancreatitis (or autoimmune pancreatitis). Since this first description, many extrapancreatic lesions have been described, even in the absence of pancreatitis and include sialadenitis, lacrimal gland inflammation, lymphadenopathy, aortitis, sclerosing cholangitis, tubulointerstitial nephritis, retroperitoneal fibrosis or inflammatory pseudotumors. Multiorgan lesions can occur synchronously or metachronously in a same patient, usually after 50 years of age. They all share common histopathological findings. The disease often responds well to corticosteroid therapy. In this literature review on IgG4-RSD, we present historical, epidemiological and clinical characteristics, and we review the biological and histological diagnostic criteria. To date there is no international validated diagnostic criteria. Pathophysiological hypothesis and therapeutic approaches are also discussed.

Immune Complex-Mediated Complement Activation in a Patient with IgG4-Related Tubulointerstitial Nephritis

A 59-year-old man was diagnosed with IgG4-related tubulointerstitial nephritis. His symptoms as well as laboratory and imaging findings were improved after initiation of steroid therapy. Serologically, he showed hypocomplementemia (C3 23 mg/dl, C4 <2 mg/dl, CH50 <7 U/ml) with high levels of IgG (IgG4 1,970 mg/dl) and immune complexes (C1q assay 8.1 μg/ml) and a low level of C1q (<2.0 mg/dl). Histologically, he also showed linear depositions of IgG, IgM, C3, C4d, C1q, membrane attack complex and all IgG subclasses (IgG1, IgG2, IgG3 and IgG4) along the tubular basement membrane, as well as granular depositions of these components in the renal interstitium. However, mannose-binding lectin and L-ficolin were not detected in these tissues. Homogeneous electron-dense deposits were observed by electron microscopy in the tubular basement membrane. It appears that the immune complexes might activate the classical pathway of the complement in both blood and local tissues in a patient with IgG4-related tubulointerstitial nephritis.

Deposition of complement C3c, immunoglobulin (Ig)G4 and IgG at the basement membrane of pancreatic ducts and acini in autoimmune pancreatitis

AIMS

Autoimmune pancreatitis (AIP) is a type of pancreatitis whose immunopathogenesis is still unknown. It has been reported that renal biopsy specimens from patients diagnosed with both AIP and tubulointerstitial nephritis reveal deposits containing complement C3, immunoglobulin (Ig)G and IgG4 at the tubular basement membranes (BMs). The aim was to investigate the deposition of complement and immunoglobulins in pancreatic tissue from AIP patients compared to non-AIP patients.

METHODS

Double immunofluorescence microscopy for C3c, IgG4 and IgG together with CK7, trypsin, collagen IV, CD31 and CD79a, as well as immunofluorescence microscopy for C1q, IgA and IgM, were performed on frozen pancreatic tissue from AIP and alcoholic chronic pancreatitis (ACP) patients.

RESULTS

In AIP patients, complement C3c, IgG4 and IgG were deposited at the collagen IV-positive BMs of pancreatic and bile ducts and of acini. In a minority of the ACP patients, weak C3c-positive BM deposits were detected, but no IgG4- or IgG-positive BM deposits were present.

CONCLUSION

The deposition of C3c, IgG4 and IgG at the BM of small- and medium-sized ducts and acini of the pancreas is characteristic of AIP. This suggests that immune complex-mediated destruction of ducts and acini play a role in the pathogenesis of AIP.

Treatment with bortezomib of a patient having hyper IgG4 disease

Hyper IgG4 disease is a recently described inflammatory disease characterized by lymphoplasmacytic infiltration leading to fibrosis and tissue destruction. Whereas most cases have been successfully treated with corticosteroids, recurrent or refractory cases may benefit from alternative therapies. Bortezomib has proven to be successful in the treatment of multiple myeloma, and its mechanism indicates that it may have merit in autoimmune or other plasmacytic disorders. We report a patient with recurrent pulmonary infiltration with IgG4 plasma cells, consistent with hyper IgG4 disease, who was successfully treated using a bortezomib-based combination with minimal therapy-related toxicities.

Clinicopathological characteristics of patients with IgG4-related tubulointerstitial nephritis

IgG4-related disease is a recently recognized multi-organ disorder characterized by high levels of serum IgG4 and dense infiltration of IgG4-positive cells into several organs. Although the pancreas was the first organ recognized to be affected by IgG4-related disorder in the syndrome of autoimmune pancreatitis, we present here clinico-pathological features of 23 patients diagnosed as having renal parenchymal lesions. These injuries were associated with a high level of serum IgG4 and abundant IgG4-positive plasma cell infiltration into the renal interstitium with fibrosis. In all patients, tubulointerstitial nephritis was the major finding. Although 14 of the 23 patients did not have any pancreatic lesions, their clinicopathological features were quite uniform and similar to those shown in autoimmune pancreatitis. These included predominance in middle-aged to elderly men, frequent association with IgG4-related conditions in other organs, high levels of serum IgG and IgG4, a high frequency of hypocomplementemia, a high serum IgE level, a patchy and diffuse lesion distribution, a swirling fibrosis in the renal pathology, and a good response to corticosteroids. Thus, we suggest that renal parenchymal lesions actually develop in association with IgG4-related disease, for which we propose the term 'IgG4-related tubulointerstitial nephritis.'